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Subject: Re: [PATCH] ext4: Check for non-zero journal inum in
 ext4_calculate_overhead
To:     Eric Sandeen <sandeen@sandeen.net>, linux-ext4@vger.kernel.org
Cc:     tytso@mit.edu, jack@suse.cz, adilger.kernel@dilger.ca,
        linux-fsdevel@vger.kernel.org, Harish Sriram <harish@linux.ibm.com>
References: <20200316093038.25485-1-riteshh@linux.ibm.com>
 <c43090c0-ce45-0737-68a5-ffe3e362012e@sandeen.net>
From:   Ritesh Harjani <riteshh@linux.ibm.com>
Date:   Thu, 19 Mar 2020 10:06:38 +0530
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On 3/18/20 11:57 PM, Eric Sandeen wrote:
> On 3/16/20 4:30 AM, Ritesh Harjani wrote:
>> While calculating overhead for internal journal, also check
>> that j_inum shouldn't be 0. Otherwise we get below error with
>> xfstests generic/050 with external journal (XXX_LOGDEV config) enabled.
>>
>> It could be simply reproduced with loop device with an external journal
>> and marking blockdev as RO before mounting.
>>
>> [ 3337.146838] EXT4-fs error (device pmem1p2): ext4_get_journal_inode:4634: comm mount: inode #0: comm mount: iget: illegal inode #
>> ------------[ cut here ]------------
>> generic_make_request: Trying to write to read-only block-device pmem1p2 (partno 2)
> 
> I think this 2nd error comes from:
> 
> static void save_error_info(struct super_block *sb, const char *func,
>                              unsigned int line)
> {
>          __save_error_info(sb, func, line);
>          ext4_commit_super(sb, 1);
> }
> 
> __save_error_info() returns if bdev_read_only() but then we try to commit the super
> anyway.  Shouldn't save_error_info() return early if bdev_read_only()?
> 
> (that'd be a separate patch, I'll send it)

Thanks. Sounds good to me.


> 
> -Eric
>